In any mode, body control is quite good, and with its active anti-roll bars—optional on non-AMG GLs, standard here—the 63 corners laughably flatly for something so massive, up to a respectable limit of 0.84 g. And the larger brakes stop the nearly three-ton truck from 70 mph in just 162 feet, which would have tied for first in our most recent sports-sedan roundup.